[PD] latency solutions... and then some

Michal Seta mis at artengine.ca
Sun Feb 7 00:07:18 CET 2010

On Wed, Feb 3, 2010 at 9:22 PM, Jeffrey Concepcion
<jeffreyconcepcion at gmail.com> wrote:
> Thanks for the suggestions, i'll deffinately be looking into your
> suggestions (i'm not familiar with some of the terms ). For now i must deal
> with what i have at home, which is an acer netbook w/ windows Xp @ 1.6 GHz,
> 1GB RAM btw! No external soundcard as of yet. i should get (in theory) a
> similar result to Pierre's so i'll be trying that approach for now

Don't be fooled by the processor Hz count. First of all, different
operating systems deal with system resources in different ways.
Whether you can get reliable, low latency performance from XP on a
netbook is beyond my experience but AFAIK, Windows and MacOS are not
as transparent and easily tuned as *NIX are.  I still use very lean
and small window manager when I want to be sure to have clean audio
without dropouts in low latency.

Beyond that, the hardware performance has a lot to do with latency.
The cheap audio interfaces that are bundled with today's computers,
especially netbooks, are not necessarily useful for for real-time, low
latency work.  They will usually require a relatively large buffers to
convert analog<->digital without hick-ups and that will add up to the
buffers needed by the audio driver, pd, CPU's workload etc.

That said, you may want to look at this thread (and/or google similar):

There are some people using linux on netbooks for realtime processing
and therefore it is possible.  YYMV, depending on your needs, your
perception of "real time" and the hardware/software configuration.
Note, that if you want to give linux a try you can grab pure:dyne or
ubuntu and install it on a USB stick or HD and take it from there
until you decide which OS works best for your particular needs.
pure:dyne will give you immediate access to media applications
(including pd) and realtime kernel.

I am actually working these days with an Acer netbook (aspire one)
running ubuntu 9.10.  Using a rt kernel improves audio performance
somewhat.  I just used a stock rt build, I could probably roll my own,
tuned to my liking but I think I am getting too old for that :).
However, the hardware cannot really keep up with very low latencies.
My focus is not on getting lowest possible latency right now so I do
not have any better advice at the moment.

half a cent from yours truly.


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